How long is a SIGMET valid after its issuance?

A SIGMET (Significant Meteorological Information) is a type of in-flight advisory that provides information on severe weather conditions which could be hazardous to aircraft. The validity of a SIGMET is crucial for pilots, as it helps them make informed decisions regarding route planning and safety.

SIGMETs are generally valid for a duration of four hours from the time of their issuance. This timeframe allows pilots to receive timely updates about significant weather phenomena such as thunderstorms, turbulence, dust storms, and volcanic ash that may affect their flight. After four hours, unless renewed, the SIGMET will expire, and its information may no longer be considered reliable.

Understanding the validity period of a SIGMET is important for pilots as they must ensure they have the latest information to maintain safety in flight operations, especially in adverse weather conditions.